New member, sorry my first post is a request for information!
 

Brief introduction; I currently ride an 09' Repsol and this is my 3rd sportbike. I live outside of Kansas City KS and am married with 6 kids between the wife and I (Brady family)!

Last weekend we got impulsive and bought her a 1990 CBR 600. The kid that sold it to us couldn't figure out why it wouldn't start, so we talked him down to $350. I did get it to crank after disassembling/cleaning the starter and popping the clutch to get it out of vapor lock. However the fuel pump is shot and our new one arrives Saturday.

In the meantime I am trying to figure out what the fuse order is on the fuse block located to the left of the handlebars. The top-most fuse (10 amp) pops EVERY TIME the ignition is turned on and I have no idea what it goes to. I believe there was originally a cover with a diagram but that is long gone.

Can anyone tell me what fuses are what so I know where to start looking for shorts from?

No takers?

Welcome.


Sorry haven't checked in for a while. There is a 10A fuse between the ignition switch and the starter button. This is a pretty simple circuit. You can get a manual if you look at the links at the top of the forum.


Popping this fuse indicates a short somewhere in the starting circuit, or something wired wrong. The back end of the circuit (hot wires from battery) is controlled by the 30A main fuse which is in the solenoid holder.


My guess is you have wires crossed or shorted from the ignition switch to the fuse block, from the fuse block to the start button or the ones that go back from there to the solenoid. Check the wires running back to the solenoid first. If someone worked on the wiring, it could be fun to figure out.

Gotcha thanks for posting! I think there has been some tomfoolery with the wiring because the bike still turns over without either of those fuses in place.

Thanks!

Looking at the wiring diagram that fuse also powers the fuel pump. Since your having a problem with the fuel pump you need to track down what is up with the wiring.


Also it's not recommended to replace the fuel pump with an aftermarket pump (the cheap ones). Most of us replace the contact block on the back of the pump for about $30. This is the common fail point.

Gotcha, I will check into that. I'm actually sitting next to the bike now having just installed the new fuel pump and changing the oil. I got it to fire up and idle momentarily before dying, but the battery ran down before I could do much with it. I believe this bike sat for awhile, and the oil in it was very low and dirty. Like, maybe 2 quarts low.... Ugh.

If it sat for a while you want to go thru all the fluids and change the oil and filter.


You need to take the air box off and check in there. Rodents go in through the air tubes in the front and will chew up the filter.


You don't want to start it until you check that. Stuff will get sucked into the engine.


Also if it sat the carbs will likely need to be cleaned. The pilot (idle) jets plug very easily...they are very small. The choke circuit gets gummed up also. They are impossible to start and keep running if the carbs are dirty.


Tank should be flushed out also to get slime from old gas out.

Oh yeah I took apart the airbox as soon as I got the bike. There was no air filter, just a wad of paper towel like material. Took apart the carbs over the weekend and they actually looked really good inside. The carb holders were brittle and split though (rubber seals between the carbs and motor). I have to replace those, they cost about 30 bucks. I was going to cheat and use rubber vacuum hose but since it's all taken apart I may as well replace them now.

I also rode it for the first time last week after the oil change. It idles horribly but actually rode well for the short time I was on it.

Good thing you bought new intake boots.


You don't want to try and make anything for this because the boots set the position of the carbs. Impossible to get them back on with something that might flex and then the air box may not fit right also. Not to mention fuel resistance.


Hard and brittle ones usually will leak vacuum and then the bike will not run right. I just had one like this and the throttle was all over the place.


Make sure you go thru the carbs completely and make sure they are clean even if they look good. If it idles bad the pilot (idle) jets are likely plugged.

Thanks! Yeah each carb was disassembled and cleaned even though they looked good. I agree about the boots; 30 bucks is worth eliminating the possibility of that being an issue.

Might also be worth running a bit of Seafoam through the gas. Does a nice job cleaning out gunk that might be clogging stuff.

Nice find if you can get it running cheap. I needed a parts bike recently (mostly for a frame) and didn't look around on here at pricing first. I ended up paying waaaay to much for a POS that barely gets above 60mph because I rode it around town and it seemed to run OK then. All I wanted was the frame and title but it would have been nice to have paid three or four hundred rather than the nine that I did pay. Live and learn, I guess.

The kid I bought it from said he had just put some in, but as clean as things were when I found it I am going to try regular gas first once I get it together.


Did you at least get some good parts from it for what you spent?


My carb boots arrived yesterday but I didn't have time to work on it.

After rebuilding some 20 sets of CBR carbs and many from other bikes, I'm not a big advocate of Sea Foam.


It may work on a bike that sat for a month and is running rough, but most of the pilot circuits I have seen are plugged pretty good. Some I had to throw the pilot jets away and buy new because they wouldn't clear even with boiling and ultrasonics.


The CBR carbs in particular are quite finicky. They have to be spotless in order to run properly. Sea Foam won't do that. It's a "quick fix" in my experience and not a very good one. I know there are people that swear by the stuff, I'm just not one of them.

+1 on what Dennis said about seafoam. I've tried it as a test and it didn't help at all. My carbs looked pretty much the same before/after.
I had an even worse experience when I used it in my weed eater. Put it in exactly to the directions. The weed eater started up fine, ran for about 30 seconds then seized up tigher than a drum. I guess in retrospect, it was a good thing as I hated that thing and wanted a new one anyway.

I guess we all have our own experiences but I have the exact opposite of yours, Dennis.

First of all, I seriously doubt that Seafoam could cause a weed-eater to seize up. Physically impossible. It is a cleaner mixed with a light oil and all it does it lubricate and dissolve. However, since correlation is not causation I suspect that it was about to freeze anyway and just happened to when you ran the cleaner.

On the carbs, I have been a Harley mechanic for about twenty years. (Caveat: the HD carbs are the exact same carbs but without the air pilot since they don't have to be balanced as it is a single carb setup. Maybe that makes a difference on chemical cleaners versus disassembly. More on that later.) However, if a bike has been sitting for a few months (Harley's never run rough after just a month of sitting but often do after six or more months) I drain the gas, flush the carb, refill with fresh gas and about an ounce of Seafoam. This works about 3/4 of the time, gets the bike running decently and then just being run regularly with fresh gas will usually clean out any residual gunk. If it doesn't take care of the problem or if the bike has been sitting for years I disassemble and rebuild right off the bat. (Got a "three years since..." project coming in this weekend)

As far as it not being a particularly good quick fix I disagree. I can put .50 worth of cleaner in and see what happens. If it doesn't work, I am out .50 and I rebuild the carb. As I said above, probably works 3/4 of the time in my fairly extensive experience.

Now, getting back to my caveat, I know a lot less about multi-carb setups. Maybe that pilot circuit is so fine that they clog up really easily and the Seafoam just never gets in there. For many applications, including EFI however, my experience has been pretty positive.

Got the title I needed. Was going to use the carbs but after the running issues with the parts bike I sent my original bank in to Wired George instead. Hopefully I'll get most of my $$ back when I get rid of the parts bike (sans frame) and then at least it will just be a learning experience rather than an expensive learning experience.

:-)

Comparing apples to oranges here. Harley engines are large capacity with single carbs.


A Honda 600cc is half the size or smaller than most Harley's. The CBR has 4 carbs...one for each cylinder. Essentially it is four 150cc engines with its own carb. The fuel circuits inside the carbs are very small. The pilot circuit is essential in starting and running. They generally won't start with a dirty pilot circuit. The pilot jets are approximately .030" These carbs are also very different from a Harley carb. I've rebuilt Harley carbs and they are nothing like a CBR carb other than the basic design. CBR carbs are very finicky to get tuned properly. Harley's will run with dirty carbs...maybe then if you can keep them running the Sea Foam has a chance to do something...not unlike just getting gas to move thru a dirty carb. Problem is most CBR's if they sit there is no way you will get anything to flow thru them.


You might have success on Harley's but I've never gotten Sea Foam to do anything on a CBR with dirty carbs...or any of my other bikes which run the gambit from 50cc's to 1200.

That was sort of my point. There were a couple blanket condemnations of Seafoam but really the issue is a specific type of design for which it isn't effective.

I agree with you totally on the CBR carbs. Given that they are both (Harley and Honda) Keihin CV carbs I figured I could easily rebuild my own bank with twenty years of experience. Tore them apart, was really careful to keep track of what went where, how many turns various screws were set at, etc. Did that four times before I finally sent them to Wired George. Gah!

Maybe I'll take the bank off the parts bike (which runs albeit poorly) and do a rebuild for practice with no pressure since it's going to be parted out anyway. See if it runs better before I tear it apart and get rid of all the bits. Can't hurt.

I would say it's more like you found "one" specific type that it works on. Some of the time.


It is not just CBR carbs...pretty much any bike I have worked on with multiple carbs. That includes metric V-Twins BTW. Also anything with a small engine. From my perspective since I rarely work on Harley's, that is pretty much everything.


My perspective is if it needs cleaning take it apart and clean it. Sorry I can't give you a thumbs up for Seafoam.

LOL. That's OK. :icon_smile:

hello. Im having similar issues. just put in a new fuel pump. Tried to start the bike and there was a loud clicking/popping sound by the fuel pump. I figured I had the wires backwards, so i reversed them and tried to start the bike. It blew a fuse immediately.

Any advice on that? Did I have the wires right the first time?

no not really, sorry. I haven't even touched this bike in months, just got too busy.

if you heard a pop I would take the pump off, use a voltmeter and see if the wires are getting power when you turn the ignition on. Sounds like you may have some exposed wire somewhere though, especially if it popped a fuse.

Pump will make some noise especially if it's dry. Is it an OEM or aftermarket pump? The aftermarket pumps are crap. They have been known to start fires. If that's what you have get a real one.